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Biomedical subjects

L Sher

Publications and source records attributed to L Sher.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evidence from the waking electroencephalogram that short sleepers live under higher homeostatic sleep pressure than long sleepers.

We used the waking electroencephalogram to study the homeostatic sleep regulatory process in human short sleepers and long sleepers. After sleeping according to their habitual schedule, nine short sleepers (sleep duration < 6 h) and eight long sleepers (> 9 h) were recorded half-hourly during approximately 40 h of wakefulness in a constant routine protocol. Within the frequency range of 0.25-20.0 Hz, spectral power density in the 5.25-9.0 and 17.25-18.0 Hz ranges was higher in short sleepers than in long sleepers. In both groups, increasing time awake was associated with an increase of theta/low-frequency alpha activity (5.25-9.0 Hz), whose kinetics followed a saturating exponential function. The time constant did not differ between groups and was similar to the previously obtained time constant of the wake-dependent increase of slow-wave activity (0.75-4.5 Hz) in the sleep electroencephalogram. In addition, the time constant of the decrease of slow-wave activity during extended recovery sleep following the constant routine did not differ between groups. However, short sleepers showed an abiding enhancement of theta/low-frequency alpha activity during wakefulness after recovery sleep that was independent of the homeostatic process. It is concluded that, while the kinetics of the homeostatic process do not differ between the two groups, short sleepers live under and tolerate higher homeostatic sleep pressure than long sleepers. The homeostat-independent enhancement of theta/low-frequency alpha activity in the waking electroencephalogram in the short sleepers may be genetically determined or be the result of long-term adaptation to chronically short sleep.

Adult↗
PubMed2001

Effects of seasonal mood changes on seasonal variations in coronary heart disease: role of immune system, infection, and inflammation.

Coronary heart disease shows a winter peak and summer trough in incidence and mortality. A substantial part of a general population experiences seasonal mood changes including winter depression. Many studies demonstrate that depression is associated with increased incidence, morbidity, and mortality of cardiovascular disease. Therefore, the author previously suggested that persons with high levels of seasonality may be at increased risk of developing or worsening of coronary heart disease in the winter. Some psychological factors promote the development of disorders of the cardiovascular system. The same psychological factors decrease immunity and promote infection. There is evidence that the infectious process is involved in the pathogenesis of coronary heart disease. Therefore, the author previously proposed that the development of infection and inflammation in the atherosclerotic plaque may be related to the psychological disorders that suppress the immune system. In this paper, the author suggests that winter depression-induced suppression of the immune system may contribute to the winter increase in incidence and mortality of cardiovascular disease.

Affect↗
PubMed2001

Etiology and pathogenesis of anxiety disorders.

The author suggests that biological abnormalities related to the development of anxiety disorders can be classified as real or relative. Individuals with 'real abnormalities' are not able to function under any circumstances, including the circumstances that are natural for humans. Persons with 'relative abnormalities' can function under the natural circumstances, but are not able to function in situations that are unnatural for humans. Unnatural situations include being in elevators, flying airplanes, driving cars, etc. The author suggests that all humans can be classified into four groups: 1. Individuals with excellent 'adaptational reserve' never develop anxiety disorders; 2. Individuals with good adaptational reserve develop anxiety disorders only if they are subjected to extremely stressful, unusual situations (e.g. being a hostage); 3. Individuals with moderate adaptational reserve develop anxiety disorders if they are exposed to unnatural situations. They have 'relative abnormalities'; 4. Individuals with poor adaptational reserve develop anxiety disorders in situations that are natural for humans. They have 'real abnormalities'.

Adaptation, Psychological↗
PubMed2001

Role of thyroid hormones in the effects of selenium on mood, behavior, and cognitive function.

Changes in thyroid function may affect mood, behavior, and cognitive function. Selenium is required for appropriate thyroid hormone synthesis, activation, and metabolism. Selenium status influences thyroid function. Selenium status also affects psychological condition and cognitive function. The author suggests that the effects of selenium status on mood, behavior, and cognition may be partly mediated by changes induced by selenium deficiency or selenium supplementation in thyroid function. Selenium deficiency decreases immunocompetence and promotes viral infections. The author proposes that patients who have a combination of depression, hypothyroidism, and increased susceptibility to viral infections, could reasonably be assessed for selenium deficiency, especially if they live in an area where the soil is low in selenium.

Affect↗
PubMed2001

Possible role of brain thyroid hormones in the effects of bright light on mood and behavior.

Considerable evidence suggests that light may significantly affect the metabolism of cerebral thyroid hormones. Changes in the brain thyroid economy, independent of peripheral changes in thyroid status, may produce considerable behavioral effects. Exposure to bright light affects the mood and behavior of healthy people and individuals with psychiatric disorders. The author suggests that the effects of bright light on mood and behavior may be partly mediated by light-induced changes in the metabolism of brain thyroid hormones.

Affect↗
PubMed2001

Possible genetic link between eating disorders and seasonal changes in mood and behavior.

Studies suggest that there is a seasonal pattern of mood fluctuations and eating behavior in patients with eating disorders. Multiple lines of evidence suggest that serotonergic pathways are involved in the mechanisms of eating disorders and seasonal changes in mood and behavior. Researchers have investigated whether variants of genes related to serotonergic transmission are associated with seasonal affective disorder (SAD) and eating disorders. There is evidence that the -1438G/A promoter polymorphism of the 5-HT2A gene plays a role in the development of SAD and eating disorders. Variation of the tryptophan hydroxylase gene may play a part in eating behavior and weight regulation in females with SAD. The author suggests that there may be a genetic link between SAD and eating disorders. It is possible that there are specific inherited personality types with a predisposition to both eating disorders and SAD.

Feeding and Eating Disorders↗
PubMed2001

Role of endogenous opioids in the effects of light on mood and behavior.

Skin cells produce endogenous opioids in response to light. This results in increased skin and plasma levels of endogenous opioids. Increased plasma levels of endogenous opioids may improve mood and affect behavior. The author suggests that improvement in mood after exposure to light may be related to the light-induced increase in levels of endogenous opioids. The author speculates that genetic factors may affect the response of skin cells to light: different people may have different genetically determined responses to natural or artificial light. The author also suggests that light may affect endogenous opioids via several different mechanisms.

Affect↗
PubMed2001

Early response to light therapy partially predicts long-term antidepressant effects in patients with seasonal affective disorder.

OBJECTIVE: To determine if the antidepressant effect of 1 hour of light therapy is predictive of the response after 1 and 2 weeks of treatment in patients with seasonal affective disorder (SAD). PATIENTS: Twelve patients with SAD. SETTING: National Institutes of Health Clinical Center, Bethesda, Md. INTERVENTIONS: Light therapy for 2 weeks. OUTCOME MEASURES: Scores on the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale (SIGH-SAD) on 4 occasions (before and after 1 hour of light therapy and after 1 and 2 weeks of therapy) in the winter when the patients were depressed. Change on typical and atypical depressive scores at these time points were compared. RESULTS: Improvement of atypical depressive symptoms after 1 hour of light therapy positively correlated with improvement after 2 weeks of therapy. CONCLUSION: In patients with SAD, the early response to light therapy may predict some aspects of long-term response to light therapy, but these results should be treated with caution until replicated.

Adult↗